Good thread. My favorite genres are probably Symphonic Metal, Melodic Death Metal (Melodeath), Power/Prog Metal, Viking/Folk Metal, and a bit of the more traditional stuff, like Thrash Metal. I don't really get into Death Metal (boring Melodeath, imo), Metalcore, Grindcore, or anything like that.
I'm also a big fan of a bunch of Classic Rock and Prog Rock, especially Japanese Prog/Gothic Rock.
Anywho, a good number of my favorites have been posted already, so I'll post some more obscure bands/song. Btw, excellent choice of Nightwish song, letstatdark!
Iced Earth - Wolf - Thrash/Power Metal - Probably my favorite band of all time.
Malice Mizer - Syunikiss - Prog/Gothic Rock - Been addicted to these guys lately!
In Flames - Brush the Dust Away - Melodeath
Soilwork - Overload - Melodeath
Dark Tranquillity - The Endless Feed - Melodeath
Amon Amarth - Cry of the Blackbirds - Melodeath with thematic influences from Viking Metal
Ensiferum - Eternal Wait - Viking/Folk Metal
Blind Guardian - A Dark Passage - Mix of Power and Prog Metal
Kamelot - March of Mephisto - Power/Prog Metal